Application of on-line HPLC-H-1 NMR to environmental samples: Analysis of groundwater near former ammunition plants

Coupling of HPLC to NMR was applied for the first time to the analysis of environmental samples, i.e., water samples from an ammunition hazardous waste site, Using the continuous now mode at very low now rates (less than or equal to 0.017 mL/min) and large volume injection (400 mu L), the confirmation of many nitroaromatic compounds could be achieved down to the microgram-per-liter level after solid phase extraction of a groundwater sample from a former ammunition production site, At a now rate of 0.006 mL/min, it is possible to detect less than 29 nmol (5 mu g) of 1,3-dinitrobenzene injected on a 75 mm x 4 mm reversed phase C-18 column (particle size, 5 mu m). The results obtained by HPLC-NMR are compared to those obtained by HPLC-PDA (photodiode array) of the same sample, demonstrating that many more compounds can be identified by the former compared to the latter method as a result of coelution of major and minor components in the HPLC chromatogram.